350 EXPERIMENT STATION EECORD. 



It is believed that ordinarily there will be little trouble experienced from this 

 disease during continuously dry seasons, but the danger is increased in wet 

 seasons, or if heavy rains follow a dry period. 



A bibliography is appended. 



A spinach disease caused by Heterosporium variabile, H. S. Reed (A 6s. in 

 Science, n. set:, 31 (11)10), Xo. 7^9, p. 638). — A brief account is given of a 

 serious leaf spot found on spinach in the trucking region about Norfolk, Va., 

 in 1909. An investigation showed that the disease was due to H. variahile. 

 The fungus apparently occurs only when other fungi have previously attacked 

 the leaves, but the fungus hyphse when once within the leaves spread in a 

 rapid manner. The investigations apparently confirm previous views regard- 

 ing the weak parasitism of this species. 



The mint rust, E. Noffray (Jour. Agr. Prat., n. set:, 19 {1910), No. 5, pp. 

 150-152). — This is a popular description of the rust Piieeinia mentJiw, which is 

 found on various members of the mint family, especially on the cultivated 

 species, Mentha piperita and J/, eitrata, together with suggestions as to its 

 control, such as the destruction of the leaves on which the secidia are borne, 

 spraying with Bordeaux mixture, and bui'ning ihe leaves which are infested 

 with the teleutospores late in the fall. 



Chlorosis of fruit trees, G. Riviere and G. Bailhache (Prog. Agr. et Vit. 

 {Ed. VEst-Centre), 31 {1910), Xo. 15, pp. -',53, -J 5-i ) .—Attention is called to the 

 fact that while pear trees are successfully grown on sandy loam soil, they grow 

 less satisfactorily on those soils containing considerable lime. This is par- 

 ticularly true of pears grafted on quinces, these trees seeming to suffer severely 

 from chlorosis. 



An investigation was undertaken to determine the proportionate amount 

 of calcium carbonate that soils could contain without its being injurious to pear 

 trees grafted upon quince stock. As a result of the investigations the authors 

 found that a content of more than 40 gm. of calcium carbonate per kilogram 

 of soil would prove injurious. In their experiments where the proportion of 

 lime was 10 gm. to 1 kg. of soil there was no evidence whatever of chlorosis. 

 Where the amount was increased to 40 gm. there was a slight indication of 

 disease, and this was much more conspicuous where the lime content amounted 

 to 170 gm. per kilogram of soil. Where the quantity of lime amounted to 280 

 gm. the planting of jiear trees in such a soil was quickly followed by their 

 death. 



The dying of fruit trees, J. Mijller and K. Stormer {Deut. Ob.stbau Ztg., 

 1910, No. 7-8, pp. 81-87, figs. 5). — ^Attention is called to the dying of cherry, 

 apple and other fruit trees, in which the following symptoms are usually seen: 

 Wilted, yellowish leaves, meager foliage, shedding of the unripe fruit, deficient 

 ripening of the fruit on the trees, death of the bark on the trunk and larger 

 branches, death of twigs, and finally the death of each branch and of the 

 entire tree. Associated with the disease, on stone fruits in particular, is the 

 appearance of gum mainly on the dying bark. A cross section of the diseased 

 limb where the bark is dying shows that the underlying heart and sap wood 

 is colored. This discoloration may be traced from the roots to the smaller 

 branches and twigs, but here the coloring is mainly in the inner heart wood, 

 while the young sap wood, cambium, and bark are as yet sound and healthy. 

 On following the coloring down into the roots, the cross section of the diseased 

 wood is seen to become less, finally ending in a dead root, usually the taproot, 

 while the lateral roots may be healthy. 



This inner coloring of the heart wood seems to be due to bacteria which 

 attack the old and dead cells and spread outward in the older branches toward 

 the bark. On trees thus diseased are found a species of fungus belonging to 



